Documentation

// HC-SR04 Ultrasonic Distance Sensor - Arduino Example
// Trig Pin: 9, Echo Pin: 10

const int trigPin = 9;
const int echoPin = 10;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  // Send a 10 microsecond pulse to trigger the sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the duration of the echo pulse
  long duration = pulseIn(echoPin, HIGH);

  // Calculate distance in cm (sound travels 34300 cm/s)
  // distance = duration / 2 / 29.1
  float distance = duration * 0.034 / 2;

  // Print the distance
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  delay(500);
}

#!/usr/bin/env python3
# HC-SR04 Ultrasonic Distance Sensor - Raspberry Pi Example
# Trig Pin: GPIO 23, Echo Pin: GPIO 24

import RPi.GPIO as GPIO
import time

trigPin = 23
echoPin = 24

GPIO.setmode(GPIO.BCM)
GPIO.setup(trigPin, GPIO.OUT)
GPIO.setup(echoPin, GPIO.IN)

try:
    while True:
        # Send trigger pulse
        GPIO.output(trigPin, GPIO.LOW)
        time.sleep(0.00001)
        GPIO.output(trigPin, GPIO.HIGH)
        time.sleep(0.00001)
        GPIO.output(trigPin, GPIO.LOW)

        # Wait for echo to start
        while GPIO.input(echoPin) == 0:
            pulse_start = time.time()

        # Wait for echo to end
        while GPIO.input(echoPin) == 1:
            pulse_end = time.time()

        # Calculate distance
        pulse_duration = pulse_end - pulse_start
        distance = pulse_duration * 17150  # cm

        print("Distance: {:.2f} cm".format(distance))
        time.sleep(0.5)

except KeyboardInterrupt:
    print("Measurement stopped by user")
finally:
    GPIO.cleanup()

# HC-SR04 Ultrasonic Distance Sensor - Pico MicroPython Example
# Trig Pin: GP15, Echo Pin: GP14

from machine import Pin, time_pulse_us
import time

trigPin = Pin(15, Pin.OUT)
echoPin = Pin(14, Pin.IN)

while True:
    # Send trigger pulse
    trigPin.value(0)
    time.sleep_us(2)
    trigPin.value(1)
    time.sleep_us(10)
    trigPin.value(0)

    # Measure pulse duration
    try:
        pulse_duration = time_pulse_us(echoPin, 1, 30000)
    except OSError:
        print("Timeout waiting for echo")
        continue

    # Calculate distance in cm
    distance = pulse_duration * 0.0343 / 2

    print("Distance: {:.2f} cm".format(distance))
    time.sleep(0.5)